He told Pollard he was unaware of the Newsnight investigation into Savile. But I pointed to a Sunday Times story which said that lawyers acting for Helen Boaden, the then head of news, told Pollard that she had informed Thompson, in December 2011, about the nature of the programme's accusations against Savile.

Therefore, if Boaden is correct, Thompson knew about the Savile allegations of child abuse before the Christmas tributes to the disc jockey were screened and some nine months before Thompson left the BBC.

I have now been sent a copy of a letter from Pollard to Conservative MP Rob Wilson, dated 14 March, in which Pollard confirms that Boaden's lawyer did make that assertion. The letter to Wilson was also reported by the Sunday Times at the weekend.

But Pollard goes on to say that the contradiction between Thompson's evidence and Boaden's evidence "does not change the conclusions I reached in my report in relation to Mr Thomson and his involvement."

Wilson is unconvinced however. He says: "I cannot see how Pollard can continue to justify his finding that he had 'no reason to doubt' Thompson's denials that he knew anything about the nature of the Savile allegations until after he [Thompson] had left the BBC."

The MP, who is PPS to health secretary Jeremy Hunt, has also written to BBC chiefs about the differences in the evidence of Thompson and Boaden.

His letter is addressed to Lord Patten, chair of the BBC Trust, the incoming director general, Lord Hall, and the acting DG, Tim Davie. It further asks them to detail how much information was withheld from the Pollard review on the grounds of legal privilege.